Hans's algorithm and MYD88(L265P) mutation may affect prognosis of primary central nervous system B-cell lymphoma.

Primary central nervous system (CNS) lymphomas account for 1.9-3% of all brain tumors, with the majority being histologically classified as primary large B-cell lymphoma of the CNS (PCNS-LBCL). PCNS-LBCL is characterized by mature germinal center-exit B cells, and most cases of this phenotype are classified as activated B-cell-like phenotype according to gene expression profiling, or as non-germinal center B-cell-like phenotype (non-GCB type) according to Hans's algorithm. Genetically, PCNS-LBCL often shows mutations in MYD88(L265P) and CD79B(Y196), and is similar to MCD or C5 in genetic subtypes. Therefore, we here investigated the clinicopathological and molecular characteristics of primary CNS B-cell lymphomas (PCNSBLs), focusing on the differences in the frequency of MYD88(L265P) and CD79B(Y196) mutations, as well as the prognosis between GCB and non-GCB types. Forty-two patients with PCNSBLs were included in this study, with 12 (28.6%) classified as GCB type and 30 (71.4%) as non-GCB type. There were no significant differences between the two types in gender, tumor location, or frequency of MYD88(L265P) and CD79B(Y196) mutations. Even after consideration of the confounding of age and the presence of R-MPV therapy, the GCB type PCNSBLs tended to exhibit better prognosis. Overall survival tended to be better in those with the GCB/MYD88(L265P) mutation (-) group, followed by the GCB/MYD88(L265P) mutation (+) group, and the non-GCB type. We speculate that Hans's algorithm and MYD88(L265P) mutation may have potential prognostic value for PCNSBLs.